Page 71 - Environmental Control in Petroleum Engineering

Drilling and Production Operations 59

Table 2-10
Typical Steam Generator Emission Levels

Operating Level S0 2 N0 2 Particulates Hydrocarbons
(Million Btu/hr) (tons/year) (tons/year) (tons/year) (tons/year)

5 21 10.3 2,9 0.43
10 66 23 6.4 0.91
20 151 53 15 2.0
50 275 96 27 3.8
Source: adapted from Sarathi, 1991.
Copyright SPE, with permission.

of fixed roof tanks, wastewater tanks, loading racks, and casing gas
from thermal recovery operations. A more detailed discussion of the
emissions from a typical onshore oil and gas production facility is
provided by Sheehan (1991) and Smith (1987).
During the operation of fixed roof tanks, volatile hydrocarbons can
be emitted into the atmosphere. There are three major sources of
emissions from these tanks: breathing losses, working losses, and
flashing losses. Breathing losses arise from a change in vapor volume
from changes in temperature and barometric pressure. Working losses
are caused by changes in the tank's fluid level. Flashing losses occur
when dissolved gas flashes to vapor from pressure drop changes
between the tank and the production line. A detailed description on
calculating emissions from fixed roof tanks has been prepared by the
American Petroleum Institute (1991).
Open tanks, sumps, and pits can be sources of emissions for volatile
hydrocarbons. The emission rates depend on the ambient temperature,
surface area of the fluid exposed to the atmosphere, and composition
of the hydrocarbon.
Another operational source of air emissions is the transfer of oil
from tanks to trucks. These emissions occur when the vapors in the
track are displaced by the entering fluid.
During production from thermal recovery projects, hot fluids are
produced at the production well. Hydrocarbon vapors, carbon dioxide,
and various sulphur compounds can be produced with the oil or from
the casing annulus. To prevent these gases from escaping into the
atmosphere, they can be collected and processed in a casing vapor
recovery system (Peavy and Braun, 1991). Such systems can remove